Composition for bluing metal



Patented Aug. 22, 1950 wUNlTED STATES PATENT. mm;

Charles F. Lawless, Lcs Angcles, ICalif.

No Drawing. Application January 18, 1947,

:Serial No. 721,886.

2 Claims.

This invention relates to a method and a composition for obtaining a blue finish on steel or iron surfaces, such as gun or rifle barrels, or the like.

It is an object of this invention to provide a method of this character that does not employ heat, but, instead, utilizes chemicals that cause a thin layer of a blue composition to act as a rust preventative, and also to enhance the appearance of the surface.

More particularly, the method or process contemplates the deposit of a plating of copper sulfide that adheres closely to the surface, by the aid of chemicals readily applied to the surface.

Although the method may be used in many ways'and by different solutions, but one form will be described hereinafter. However, the scope of the invention is best defined by the appended claims.

In practicing the method, two general steps are performed. The first step is to deposit a plating of copper; and the second is to convert the copper to copper sulfide.

The copper deposit is formed by the aid of a solution preferably of the following:

Proportions by weight in percent.

Distilled water 87.974

The proportions may be varied to some extent, although those given are preferred. For example, each ingredient may be doubled or halved, the amount of water being correspondingly adjusted to make the whole. However, the amount of hydrochloric acid should always exceed the amount of sulfuric acid.

Before using the solution, the surface to be treated is freed from grease, rust, and foreign matter. If necessary, fine emery, or other abrasive, can be used, and the surface finish polished with steel wool. The smoother and brighter the surface, the more satisfactory will be the finish.

After the surface is thus made ready for the solution, a swab is wetted in the solution, excess moisture being squeezed out of the swab. Then the swab is applied evenly, until an even, slightly reddish color appears. The surface is then dried, and polished with steel wool or other very fine abrasive. If the reddish color has partially or wholly disappeared, or shows spotted areas, the solution may be applied again, or several times, polishing being effected after each application as before. Usually not more than two applications are required.

The specific ingredients thus affix a thin copper plating to the surface. The layer is very tightly iadhdered by virtue of some of the ingredients utiize The copper sulfate is the source of copper; the tartaric and acetic acids act as buffer solutions preventing spongy deposition; the stannous chloride is a surface activator that makes the coating smoother and harder; the lauryl sulfate serves to ensure wetting by the solution; and the sulfuric and hydrochloric acids are used for etching and cleaning the surface.

After the surface has thus been treated, the copper layer is reconverted to copper sulfide, as by the application of a solution of ammonium polysulfide of any reasonable strength up to saturation. It may be applied by a swab dipped into the solution, the excess liquid being squeezed out. Used swabs should not be dipped back into either solution, a new swab for each application being desirable. The application should be in even strokes, being sure to cover all the surface; and, while the surface is wet, it is rubbed lightly with steel wool the entire wet surface, overlapping the untreated part, thus giving a blend, eliminating spots or stopping-off marks. This rubbing should continue until the surface begins to dry, then allowed to stand a minute or longer and polished with a cloth; or it may be lightly polished with fine steel wool.

In the following claims, the term a solution consisting essentially of copper sulphate" refers to any solution in which any or all of the elements specified hereinabove may be utilized in the proportions set forth herein. Furthermore, where reference is made in the claims to a water solution, such reference means that the remainder of the solution is made up substantially entirely of water.

The inventor claims:

1. A composition of the following ingredients in water: about five percent by weight of copper sulfate; a total of about five percent by weight of sulfuric and hydrochloric acid; lauryl sulfate of the order of one-thousandth of one per cent; about one percent by weight of tartaric acid; about one-fourth of one percent by Weight of stannous chloride; and about one-half percent by weight of glacial acetic acid.

2. A composition of the following ingredients in water: about five percent by weight of copper sulfate; a total of about five percent by weight of sulfuric and hydrochloric acid; lauryl sulfate of the order of one-thousandth of one percent; about one percent by weight of tartaric acid; about one-fourth of one percent by weight of stannous chloride; and about one-half percent by weight of glacial acetic acid; said hydrochloric acid exceeding said sulfuric acid. I 7 7 CHARLES E. LAWLESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,317,351 Chadwick et a1. Sept. 30, 1919 1,587,637 Ferguson June 8, 1926 Number Number 15 2,561

Name Date Brunner Sept. 15, 1936 Leonard May 25, 1937 Tucker Feb. 14, 1939 Neilson Jan. 7, 1941 Tanner June 10, 1941 Snow Nov. 25, 1941 Clark et a1. July 7, 1942 Tanner et a1. Nov. 17, 1942 Vande Bunte June 5, 1945 Beaver Dec. 18, 1945 FOREIGN PATENTS Country Date Great Britain June 6, 1855 

1. A COMPOSITION OF THE FOLLOWING INGREDIENTS IN WATER: ABOUT FIVE PERCENT BY WEIGHT OF COPPER SULFATE; A TOTAL OF ABOUT FIVE PERCETN BY WEIGHT OF SUILFURIC AND HYDROCHLORIC ACID; LAURYL SULFATE OF THE ORDER OF ONE-THOUSANDTH OF ONE PER CENT; ABOUT ONE PERCENT BY WEIGHT OF TARTARIC ACID; ABOUT ONE-FOURTH OF ONE PERCENT BY WEIGHT OF STANNOUS CHLORIDE; AND ABOUT ONE-HALF PERCENT BY WEIGHT OF GLACIAL ACETIC ACID. 